Drum electrode, method for producing drum electrode, plating device, method for producing resin molded body, and method for producing metal porous body

ABSTRACT

A drum electrode, which is used for a device configured to plate a surface of a long base material having electrical conductivity with a metal, includes a power feeding layer, an insulating layer which covers a surface of the power feeding layer, and a projecting electrode which projects from the surface of the insulating layer and is electrically connected to the power feeding layer, in which the projecting electrode is provided linearly in the circumferential direction of the drum electrode.

TECHNICAL FIELD

The present invention relates to a drum electrode which is used forplating the surface of a resin molded body having a three-dimensionalnetwork structure with a metal in a plating tank. The invention furtherrelates to a method for producing the drum electrode, and a platingdevice, a method for producing a resin molded body, and a method forproducing a metal porous body, each using the drum electrode.

BACKGROUND ART

In recent years, metal porous bodies having a three-dimensional networkstructure have been widely used in electrodes of batteries, variousfilters, catalyst carriers, and the like. A metal porous body isgenerally obtained by imparting electrical conductivity to the surfaceof a resin molded body having a three-dimensional network structure,such as foamed urethane or foamed melamine, electroplating the surfaceof the resin molded body with a metal, and then removing the resinmolded body by heat treatment or the like.

In the case where a resin molded body to which electrical conductivityhas been imparted has a high electrical resistance, in order toefficiently perform electroplating with a metal, it is preferable tofeed power to the resin molded body in a plating solution using a drumelectrode. However, in the case of a resin molded body having athree-dimensional network structure, a plating solution passes throughinterconnected pores of the resin molded body. Therefore, when a drumelectrode whose entire surface is electrically conductive is used, ametal is electrodeposited not only on the resin molded body, but also onthe surface of the drum electrode. Consequently, current efficiency isdecreased, and furthermore, since it is difficult to remove the metalelectrodeposited on the surface of the drum electrode, it becomesnecessary to periodically replace the drum electrode.

Accordingly, metal electroplating is performed on the surface of a resinmolded body having a three-dimensional network structure, for example,using a device shown in FIG. 8. In FIG. 8, reference sign 80 denotes adevice for producing a metal porous body, reference sign 81 denotes adrum electrode serving as a cathode, reference sign 82 denotes aprojection made of an electrically conductive material formed on thedrum electrode 81, reference sign 83 denotes an anode, reference sign 84denotes a plating tank, reference sign 85 denotes a plating solutioncontained in the plating tank 84, and reference sign W denotes a longresin molded body (work) having a three-dimensional network structure towhich electrical conductivity has been imparted and which is to beplated.

The drum electrode 81 is immersed, at the lower portion thereof, in theplating solution 85 and rotates at the same velocity as the conveyingvelocity of the work W. The portion other than the projections 82 madeof the electrically conductive material has an insulating property.During plating, the projections 82 penetrate into pores of the work Wwhich is a porous body, and metal plating is performed in the vicinityof the projections 82. Therefore, it is possible to sufficiently platethe work W including the inside thereof while avoiding electrodepositionof the metal on the surface of the drum electrode 81.

A drum electrode used in such a device for producing a metal porous bodyis described, for example, in Japanese Unexamined Patent ApplicationPublication No. 1-255686 (Patent Literature 1) or Japanese UnexaminedPatent Application Publication No. 2013-007069 (Patent Literature 2).

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 1-255686

PTL 2: Japanese Unexamined Patent Application Publication No.2013-007069

SUMMARY OF INVENTION Technical Problem

In the existing drum electrode described above, while preventingelectrodeposition of a metal on the surface of the drum electrode, it ispossible to electrodeposit the metal uniformly on the surface of a resinmolded body having a three-dimensional network structure. However, thereis room for improvement from the viewpoint that the method for producingthe drum electrode itself is complicated and costly and that it takes alot of time and trouble to perform a cutting process in order to adjustthe height of electrically conductive projections on which the metal hasbeen electrodeposited during the operation.

Accordingly, it is an object to provide a drum electrode with which ametal can be electrodeposited on the surface of a long base material ina plating tank, which can be produced by an easy method, and in whichthe maintenance during the operation is easy; and a method for producingthe same. It is another object to provide a plating device, a method forproducing a resin molded body, and a production method, each using sucha drum electrode.

Solution to Problem

In order to solve the problem described above, a drum electrodeaccording to an embodiment of the present invention employs thefollowing structure:

(1) That is, a drum electrode according to an embodiment of the presentinvention is a drum electrode for a device configured to plate a surfaceof a long base material having electrical conductivity with a metal, thedrum electrode including a power feeding layer, an insulating layerwhich covers a surface of the power feeding layer, and a projectingelectrode which projects from the surface of the insulating layer and iselectrically connected to the power feeding layer, in which theprojecting electrode is provided linearly in the circumferentialdirection of the drum electrode.

Advantageous Effects of Invention

According to the embodiment described above, it is possible to provide adrum electrode with which a metal can be electrodeposited on the surfaceof a long base material in a plating tank, which can be produced by aneasy method, and in which the maintenance during the operation is easy;and a method for producing the same. It is also possible to provide aplating device, a method for producing a resin molded body, and a methodfor producing a metal porous body, each using such a drum electrode.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing an example of a structure of a drumelectrode according to the present invention.

FIG. 2 is a schematic view showing an example of a process for producinga drum electrode according to the present invention.

FIG. 3 is a schematic view showing an example of a structure of aring-shaped insulating disk having a through-hole in the center thereof.

FIG. 4 is an enlarged cross-sectional view schematically showing asurface portion of an example of a drum electrode according to thepresent invention.

FIG. 5 is an enlarged cross-sectional view schematically showing asurface portion of another example of a drum electrode according to thepresent invention.

FIG. 6 is an enlarged cross-sectional view schematically showing asurface portion of a drum electrode in Example 2.

FIG. 7 is an enlarged cross-sectional view schematically showing asurface portion of a drum electrode in Example 3.

FIG. 8 is a schematic view showing an example of an existing device forproducing a metal porous body.

DESCRIPTION OF EMBODIMENTS

First, contents of embodiments of the present invention are enumeratedand described.

(1) A drum electrode according to an embodiment of the present inventionis a drum electrode for a device configured to plate a surface of a longbase material having electrical conductivity with a metal, the drumelectrode including a power feeding layer, an insulating layer whichcovers a surface of the power feeding layer, and a projecting electrodewhich projects from the surface of the insulating layer and iselectrically connected to the power feeding layer, in which theprojecting electrode is provided linearly in the circumferentialdirection of the drum electrode.

When the drum electrode described in the item (1) is used, by feedingpower to the long base material in a plating tank, a metal can beelectrodeposited on the surface of the base material. Furthermore, as aresult of thorough studies by the present inventors, it has been foundthat by providing a projecting electrode, which is linearly shaped inthe circumferential direction, on the surface of the drum electrode, itis possible to perform electroplating with a metal with sufficientuniformity on a long base material in a plating tank.

That is, by using the structure described in the item (1), it ispossible to electrodeposit a metal on the surface of a long basematerial in a plating tank, and it is possible to provide a drumelectrode which can be produced by an easy method, and in which themaintenance during the operation is easy.

In the drum electrode according to the embodiment of the presentinvention, the expression “the projecting electrode is providedlinearly” covers both the case of a continuous linear shape extending inthe circumferential direction and the case of a discontinuous linearshape with a notch being formed partially. Furthermore, the projectingelectrode is not necessarily completely parallel to the circumferentialdirection, but may be inclined at an angle of 60° or less and formed ina helical shape.

(2) Furthermore, in the drum electrode according to the embodiment ofthe present invention, preferably, the height of the projectingelectrode varies with the location of the projecting electrode on thedrum electrode.

As will be described later, in the drum electrode according to theembodiment of the present invention, depending on the maintenance methodduring use, the height of the projecting electrode may vary with thelocation of the projecting electrode. Even such a drum electrode can besuitably used for metal plating on the surface of the base material.Therefore, during use of the drum electrode, the number of maintenancemethods to choose from increases.

(3) Furthermore, in the drum electrode according to the embodiment ofthe present invention, the base material is preferably a resin moldedbody having a three-dimensional network structure.

The drum electrode according to the embodiment of the present inventioncan also be suitably used for a long base material having a lowelectrical resistance, such as a copper plate. However, in the casewhere the base material is a resin molded body having athree-dimensional network structure, a higher effect can be achieved.For example, in the case where the base material is a resin molded bodyhaving a three-dimensional network structure that has undergoneelectrical conduction treatment by application of carbon, because of itshigh electrical resistance, the plating voltage increases in theexisting drum electrode, and there is a possibility that the resin whichis the base material will be burned off. Furthermore, it is difficult toform a plating film uniformly on the central portion in the thicknessdirection of the resin molded body or a surface opposite the surface incontact with the drum electrode. In contrast, in the drum electrodeaccording to the embodiment of the present invention, since a projectingelectrode is provided linearly in the circumferential direction, platingcan be performed directly in a liquid, and therefore, the resistance ofthe base material can be decreased. Furthermore, it is possible to forma plating film uniformly even on the inside of the porous portion of theresin molded body.

Hereinafter, the resin molded body having a three-dimensional networkstructure may also be simply referred to as a resin molded body.

(4) A method for producing a drum electrode according to an embodimentof the present invention includes a step of covering a surface of acolumnar power feeding layer with an insulating layer, a step ofpartially removing the surface of the insulating layer linearly in thecircumferential direction so as to expose the surface of the powerfeeding layer, and a step of plating the linearly exposed surface of thepower feeding layer with a metal to form a projecting electrode so as tobe higher than the surface of the insulating layer.

(5) A method for producing a drum electrode according to anotherembodiment of the present invention includes a step of alternatelystacking ring-shaped insulating disks and ring-shaped metal disks, eachhaving a through-hole in the center thereof, to form a cylindricalshape; and a step of inserting a columnar power feeding member into thethrough-holes of the insulating disks and the metal disks, followed byfixing.

By using the method for producing a drum electrode described in the item(4) or (5), it is possible to easily produce the drum electrodeaccording to the embodiment of the present invention described in theitem (1).

(6) A plating device according to an embodiment of the present inventionis configured to plate a surface of a long base material, to whichelectrical conductivity has been imparted, with a metal using a drumelectrode provided in a plating tank, in which the drum electrode is thedrum electrode described in any one of the items (1) to (3).

The plating device described in the item (6) uses the drum electrodedescribed in the item (1) or (2). Therefore, excessive maintenance isnot required compared with the existing plating device, and it ispossible to easily produce a resin structure having a metal plating filmon the surface thereof.

(7) A method for producing a resin structure according to an embodimentof the present invention includes a step of imparting electricalconductivity to a surface of a long base material made of a resin, and astep of plating the surface of the base material with a metal using adrum electrode provided in a plating tank to obtain a resin structurehaving a metal plating film on the surface thereof, in which the drumelectrode is the drum electrode described in the item (1) or (2).

(8) A method for producing a metal porous body according to anembodiment of the present invention includes a step of impartingelectrical conductivity to a surface of a resin molded body having athree-dimensional network structure, a step of plating the surface ofthe resin molded body with a metal using a drum electrode provided in aplating tank to obtain a resin structure, and a step of removing theresin molded body from the resin structure to obtain a metal porousbody, in which the drum electrode is the drum electrode described in theitem (1) or (2).

In the method for producing a resin structure described in the item (7)and the method for producing a metal porous body described in the item(8), since the drum electrode described in any one of the items (1) to(3) is used, the cost required for producing the drum electrode can bereduced, and it is possible to more inexpensively provide a resinstructure or a metal porous body. Furthermore, since the drum electrodecan be relatively easily maintained, the burden of control during theoperation can be reduced, and it is possible to more easily provide aresin structure or a metal porous body.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Specific examples of a drum electrode and the like according to theembodiments of the present invention will be described below. It isintended that the scope of the present invention is not limited to theexamples, but is determined by appended claims, and includes allvariations of the equivalent meanings and ranges to the claims.

<Drum Electrode>

A drum electrode according to an embodiment of the present invention isa drum electrode for a device configured to plate a surface of a longbase material having electrical conductivity with a metal. As shown inFIG. 1, the drum electrode includes a power feeding layer 11, aninsulating layer 12, and projecting electrodes 13. The insulating layer12 covers the surface of the power feeding layer 11, and the projectingelectrodes 13 are formed so as to project from the surface of theinsulating layer 12 and are electrically connected to the power feedinglayer 11. The projecting electrodes 13 are formed linearly in thecircumferential direction of the drum electrode 1.

The power feeding layer 11 is not particularly limited as long as it iselectrically conductive, and various metals can be suitably used.Furthermore, the power feeding layer 11 may have a single-layerstructure or a layered structure including two or more layers. That is,even when another electrical conductive material is disposed on thesurface of the power feeding layer 11 serving as the center of the drumelectrode 1, it is acceptable as long as the individual layerssufficiently adhere to each other such that the layers do not moverelatively and are electrically connected to each other. In the casewhere the degree of adhesion between the layers is low, the rotary driveis not sufficiently transmitted when the drum electrode 1 is rotated.Therefore, the degree of adhesion between the layers is preferably high.

The insulating layer 12 has an insulating property and is stable to aplating solution with which it is in contact in a plating tank where thedrum electrode 1 is placed. For example, a resin, such as an epoxyresin, a silicon resin, or a fluororesin, can be suitably used as theinsulating layer. In the case where the surface of the resin molded bodyis aluminum plated, the fluororesin is particularly preferable among theresins described above. Furthermore, an anodic oxide film formed on thesurface of the power feeding layer 11 can also be suitably used.

The projecting electrode 13 is not particularly limited as long as it iselectrically conductive, and various metal materials can be suitablyused, but the projecting electrode 13 is preferably made of the samemetal as the metal to be plated on the surface of the base material.Specifically, for example, a projecting electrode made of nickel issuitably used for nickel plating, and a projecting electrode made ofaluminum is suitably used for aluminum plating.

In FIG. 1, the projecting electrodes 13 are each continuously formedlinearly parallel to the circumferential direction of the drum electrode1. Accordingly, in the drum electrode 1, the insulating layers 12 andthe projecting electrodes 13 are alternately arranged. Furthermore, in adrum electrode according to the embodiment of the present invention, theprojecting electrodes 13 may be continuously formed in thecircumferential direction in a closed state, or the projectingelectrodes 13 may be discontinuous with a notch being formed partially.In the case where a notch exists on a projecting electrode 13, thelength of the notch is preferably as small as possible, and ispreferably smaller than the length of the continuous portion of theprojecting electrode.

Furthermore, the projecting electrodes 13 may be formed parallel to thecircumferential direction or may be formed with some inclination withrespect to the circumferential direction. In the case where acontinuous, linear projecting electrode has an inclination with respectto the circumferential direction, the projecting electrode 13 is formedin a helical shape on the surface of the drum electrode 1. The anglebetween the projecting electrode 13 and the circumferential direction ispreferably as small as possible, and is preferably 60° or less.

By increasing the width of the insulating layer 12 relative to the widthof the projecting electrode 13, current efficiency can be increased. Onthe other hand, for example, in the case where the base material is onesuch as a resin molded body that has undergone electrical conductiontreatment by application of carbon, which has a large electricalresistance, the covering power of metal plating tends to be decreased.Furthermore, when the width of the insulating layer 12 is decreasedrelative to the width of the projecting electrode 13, electricalresistance decreases, and the covering power of metal plating on thebase material can be increased, but current efficiency tends to bedecreased.

Therefore, taking the above-mentioned points into consideration, thewidth of the insulating layer 12 and the width of the projectingelectrode 13 may be appropriately set depending on the material andthickness of the base material to be plated with a metal, the type ofmetal used for plating, or the like. For example in the case wherealuminum plating is performed in a molten salt on a foamed urethaneresin to which electrical conductivity has been imparted, by alternatelyarranging insulating layers 12 with a width of about 4 to 12 mm andprojecting electrodes 13 with a width of about 1 to 4 mm, electroplatingcan be performed satisfactorily.

The projecting electrode 13 needs to project from the surface of theinsulating layer 12. The reason for this is that when the drum electrode1 and the base material are brought into contact with each other, theprojecting electrode 13 is in contact with the base material withoutfail so that power feeding can be performed. In particular, in the casewhere the base material is one such as a resin molded body having athree-dimensional network structure to which electrical conductivity hasbeen imparted, which has a large electrical resistance and in which itis difficult to form a plating film uniformly even on the inside of theporous portion thereof, it is necessary to bring the projectingelectrode 13 and the base material into contact with each othersufficiently. The projecting height of the projecting electrode 13 fromthe insulating layer 12 is not particularly limited, but is preferablymore than 0 mm to about 2 mm, more preferably about 0.2 to 1.5 mm, andstill more preferably about 0.5 to 1 mm. In this case, the projectingelectrode 13 can be sufficiently brought into contact with the basematerial.

When the projecting electrode is lower than the insulating layer, sincethe surface of the base material and the projecting electrode are not incontact with each other, it is not possible to electroplate the surfaceof the base material with a metal. However, since the drum electrodeaccording to the embodiment of the present invention is provided in aplating tank filled with a plating solution, when the plating solutionand the projecting electrode are in contact with each other during theoperation, the metal starts to be electrodeposited on the surface of theprojecting electrode to increase the height of the projecting electrode,and as a result, the projecting electrode projects from the surface ofthe insulating layer. In such a state, since the projecting electrodeand the base material come into contact with each other, power feedingbecomes possible, and it is possible to electroplate the surface of thebase material with the metal.

As described above, in the drum electrode according to the embodiment ofthe present invention, since the metal is electrodeposited on thesurface of the projecting electrode during use, the height of theprojecting electrode increases relative to the insulating layer.Therefore, when the drum electrode according to the embodiment of thepresent invention is used, preferably, a cutting bit is provided at apredetermined position from the surface of the insulating layer.Thereby, even when the metal is electrodeposited on the projectingelectrode to increase the height of the projecting electrode, if theheight of the projecting electrode exceeds the predetermined level, theexcess portion will be cut by the bit, thus preventing the projectingelectrode from excessively projecting.

The cutting bit may be provided on the upper side of the drum electrode(the side opposite to the plating tank). Furthermore, a cutting bit maybe provided and fixed on the upper side of each projecting electrode.Alternatively, a plurality of cutting bits may be provided on the upperside of the drum electrode so as to be movable in a direction orthogonalto the circumferential direction. In the case where the cutting bitsmove in a direction orthogonal to the circumferential direction, theheight of the projecting electrodes from the surface of the insulatinglayer does not become uniform. Even in such a state, it is possible toform a plating film uniformly on the surface of the base material.

Furthermore, the surface of the projecting electrode is preferablyrough, rather than smooth, because good interlocking with the basematerial can be achieved. The method for roughening the surface of theprojecting electrode is not particularly limited, and any method thatforms appropriate irregularities may be used. In this case, the surfaceroughness may be on the order of micrometers (μm). Examples of themethod for roughening the surface of the projecting electrode include amethod in which the surface is polished with a coarse file, a method inwhich a thin plating film is formed, an etching method, and a method inwhich dissolution is performed using an acid or alkali. Furthermore, inthe case where a metal is electrodeposited on the surface of theprojecting electrode to roughen the surface, the roughened state can beused as it is.

As the base material, any long base material whose surface is to beplated with a metal may be used. Examples thereof include a resin sheetto which electrical conductivity has been imparted by application ofcarbon or the like. As the resin sheet, for example, a vinyl chloridesheet or the like may be used.

Furthermore, as described above, in the case where the base material isa resin molded body having a three-dimensional network structure, theperformance of the drum electrode according to the embodiment of thepresent invention is highly exhibited.

As the resin molded body having a three-dimensional network structure,for example, a foamed resin molded body produced using polyurethane, amelamine resin, or the like can be used. Although expressed as thefoamed resin molded body, a resin molded body having any shape can beselected as long as it has continuous pores (interconnected pores). Forexample, a body having a nonwoven fabric-like shape in which resinfibers, such as polypropylene or polyethylene, are entangled with eachother can be used instead of the foamed resin molded body.

Furthermore, the type of metal used for plating is not particularlylimited, and can be appropriately selected according to the intendedpurpose of the surface treatment of the base material. Examples thereofinclude aluminum, copper, nickel, zinc, tin, chromium, silver, and gold.

By using the drum electrode according to the embodiment of the presentinvention, even in the case where the base material is a resin moldedbody having a three-dimensional network structure, it is possible toelectrodeposit a metal uniformly on the surface of the base material ina plating tank. As will be described later, the drum electrode itselfcan be produced by an easy method, and moreover, the burden ofmaintenance during use can be reduced.

<Method for Producing Drum Electrode>

(Production Method According to Embodiment 1)

The drum electrode according to the embodiment of the present inventiondescribed above can be produced by a method for producing a drumelectrode, which includes a step of covering a surface of a columnarpower feeding layer with an insulating layer (insulating layer formationstep), a step of partially removing the surface of the insulating layerlinearly in the circumferential direction so as to expose the surface ofthe power feeding layer (insulating layer partial removal step), and astep of plating the linearly exposed surface of the power feeding layerwith a metal to form a projecting electrode so as to be higher than thesurface of the insulating layer (projecting electrode formation step).

[Insulating Layer Formation Step]

First, a columnar, electrically conductive material serving as a powerfeeding layer is prepared. As described above, the material for thepower feeding layer is not particularly limited as long as it iselectrically conductive, and various metals can be suitably used.Furthermore, the power feeding layer may have a single-layer structureor a layered structure including two or more layers.

Subsequently, the columnar power feeding layer is entirely coated bydisposing an insulating layer on the surface thereof. The insulatinglayer may be formed with a large thickness when the diameter of thepower feeding layer is small relative to the diameter of the drumelectrode to be produced. The insulating layer may be formed with asmall thickness when the power feeding layer includes a plurality oflayers and the diameter of the power feeding layer is close to thediameter of the drum electrode.

As described above, the insulating layer has an insulating property andis stable to a plating solution with which it is in contact in a platingtank where the drum electrode is placed. For example, the insulatinglayer can be formed by a method in which an insulating resin is used, amethod in which an anodic oxide film is formed on the surface of thepower feeding layer, or the like.

[Insulating Layer Partial Removal Step]

By undergoing the step described above, the entire surface of the powerfeeding layer is coated with the insulating layer. A groove is formed ina portion of the surface of the insulating layer in which a projectingelectrode is to be formed. The insulating layer is removed until thegroove reaches the surface of the power feeding layer located under theinsulating layer.

In this step, by forming a plurality of grooves, each groove beingcontinuously formed parallel to the circumferential direction, it ispossible to produce a drum electrode in which insulating layers andprojecting electrodes are alternately arranged. Furthermore, when eachgroove is not completely continuous in the circumferential direction anda portion without the groove is provided, it is possible to form aprojecting electrode having a notch partially formed therein.Furthermore, when a groove is continuously formed at a certain angle(60° or less) with respect to the column direction, it is possible toform a projecting electrode which projects helically on the surface ofthe drum electrode.

[Projecting Electrode Formation Step]

A projecting electrode is formed on the exposed portion of the surfaceof the power feeding layer in which the groove has been formed in theinsulating layer as described above. The projecting electrode is notparticularly limited as long as it is electrically conductive, andvarious metal materials can be suitably used. Furthermore, as describedabove, the projecting electrode is preferably made of the same metal asthe metal to be plated on the base material.

The method for forming the projecting electrode is not particularlylimited. For example, the projecting electrode can be formed by platingthe exposed portion of the surface of the power feeding layer with ametal. The plating method may be non-electrolytic plating orelectrolytic plating. The plating is stopped when the metal plating thathas started to grow on the exposed portion of the surface of the powerfeeding layer projects from the surface of the insulating layer.

(Production Method According to Embodiment 2)

The drum electrode according to the embodiment of the present inventiondescribed above can also be produced by a method for producing a drumelectrode, which includes a step of alternately stacking ring-shapedinsulating disks and ring-shaped metal disks, each having a through-holein the center thereof, to form a cylindrical shape; and a step ofinserting a columnar power feeding member into the through-holes of theinsulating disks and the metal disks, followed by fixing.

In this method, as shown in FIG. 2, ring-shaped insulating disks 22having a through-hole in the center thereof and ring-shaped metal disks23 having a through-hole in the center thereof are produced andalternately arranged in a concentric fashion to form a cylindricalshape. A columnar power feeding member is inserted into thethrough-holes in the center and fixed firmly.

The insulating disks 22 and the metal disks 23 can be fixed together,for example, by fastening with bolts, application of an adhesive, or thelike. Furthermore, fixing with the power feeding member which has beeninserted into the through-hole can be performed in the same manner usingbolts or an electrically conductive adhesive.

The diameter of the metal disk 23 is preferably larger than the diameterof the insulating disk 22. However, even in the case where the diameterof the metal disk 23 is equal to or smaller than the diameter of theinsulating disk 22, after the power feeding member has been inserted, asin the method described above, the surface of the metal disk 23 may beplated with a metal.

Since the insulating disk 22 serves as the insulating layer describedabove, a material having an insulating property and is stable to aplating solution with which it is in contact in a plating tank where thedrum electrode is placed can be used for the insulating disk 22.

Since the metal disk 23 serves as the projecting electrode describedabove, the material for the metal disk 23 is not particularly limited aslong as it is electrically conductive, and various metal materials canbe suitably used. Preferably, the metal is the same as the metal to beplated on the base material.

As described above, the power feeding layer is not particularly limitedas long as it is electrically conductive, and various metals can besuitably used. Furthermore, the power feeding layer may have asingle-layer structure or a layered structure including two or morelayers.

Furthermore, the insulating disk 22 may be a single ring-shaped disk ora disk formed by combining a plurality of plates. For example, theinsulating disk 22 may be formed by combining a plurality of dividedsectoral insulating disks (insulating layers) 32 as shown in FIG. 3.However, in the case where sectoral ones are used, joints must be weldedor the like so that no voids are formed. When the joint portion has avoid, the plating solution enters the void, and plating grows in thevoid. Therefore, a conductive portion that is continuous in a directionorthogonal to the circumferential direction is formed on the surface ofthe drum electrode. When such a conductive portion that is continuous ina direction orthogonal to the circumferential direction is formed, thecurrent concentrates on the conductive portion, which may causeproblems. For example, in the case where the base material is a resinmolded body, the base material may be burned off.

In such a manner, the drum electrode according to the embodiment of thepresent invention can be produced. In accordance with these methods, itis possible to produce the drum electrode very easily compared with theexisting drum electrode.

FIGS. 4 and 5 are each an enlarged cross-sectional view of a drumelectrode obtained by the method described above. FIG. 4 shows anexample in which a power feeding layer is formed by stacking a pluralityof layers, the surface portion thereof is covered with an insulatinglayer 42, grooves are provided in the insulating layer 42, andprojecting electrodes 43 are formed in the grooves. Furthermore, FIG. 5shows an example in which the drum electrode is produced by alternatelyarranging insulating disks 52 and metal disks 53, followed by fixing.

<Plating Device>

A plating device according to an embodiment of the present invention isconfigured to plate a surface of a long base material, to whichelectrical conductivity has been imparted, with a metal using a drumelectrode provided in a plating tank, in which the drum electrode is thedrum electrode according to the present invention described above.

The plating device according to the embodiment of the present inventioncan have the same basic structure as that of the existing device, forexample, shown in FIG. 8, as long as the drum electrode according to theembodiment of the present invention is used. That is, the plating devicehas a structure in which, in a plating tank filled with a platingsolution, the drum electrode according to the embodiment of the presentinvention is provided as a cathode and a metal for plating is providedas an anode. Furthermore, as described above, preferably, a cutting bitis provided on the upper side of the plating device so that it ispossible to partially cut the projecting electrode on which the metalhas been electrodeposited and whose height has been increased during theoperation.

<Method for Producing Resin Structure>

A method for producing a resin structure according to an embodiment ofthe present invention includes a step of imparting electricalconductivity to a long base material made of a resin, and a step ofplating a surface of the base material with a metal using a drumelectrode provided in a plating tank to obtain a resin structure havinga metal plating film on the surface thereof, in which the drum electrodeis the drum electrode according to the embodiment of the presentinvention described above.

In the method for producing a resin structure according to theembodiment of the present invention, as long as the drum electrodeaccording to the embodiment of the present invention is used as the drumelectrode, the other steps can be performed as in the existing methodfor producing a resin structure.

Furthermore, any long base material made of a resin can be used as thebase material as long as the surface thereof is to be plated with ametal as described above. As the method for imparting electricalconductivity to the surface of the base material, for example, a methodmay be used in which carbon powder formed into a paste is applied to thesurface of the base material.

<Method for Producing Metal Porous Body>

A method for producing a metal porous body according to an embodiment ofthe present invention includes a step of imparting electricalconductivity to a resin molded body having a three-dimensional networkstructure, a step of plating a surface of the resin molded body with ametal using a drum electrode provided in a plating tank to obtain aresin structure, and a step of removing the resin molded body from theresin structure to obtain a metal porous body, in which the drumelectrode is the drum electrode according to the embodiment of thepresent invention described above. In the method for producing a metalporous body according to the embodiment of the present invention, aslong as the drum electrode according to the embodiment of the presentinvention is used as the drum electrode, the other steps can beperformed as in the existing method for producing a resin structure.

As the resin molded body having a three-dimensional network structureserving as the base material, as described above, a foamed resin moldedbody can be suitably used. In addition, it is also possible to suitablyuse a body having a nonwoven fabric-like shape in which resin fibers areentangled with each other, and a resin molded body in any shape havingcontinuous pores.

Furthermore, the method for imparting electrical conductivity to theresin molded body is not particularly limited. When the drum electrodeaccording to the embodiment of the present invention is used, it ispossible to perform electroplating satisfactorily even on a basematerial having a relatively large resistance, such as the one obtainedby application of carbon. The method of application of carbon is notparticularly limited, and a known method can be employed.

EXAMPLES

The present invention will be described in more detail below on thebasis of examples. However, the examples are merely illustrative and thedrum electrode and the like of the present invention are not limitedthereto. It is intended that the scope of the present invention isdetermined by appended claims, and includes all variations of theequivalent meanings and ranges to the claims.

Example 1

<Production of Drum Electrode 1>

24 Disks made of aluminum with a thickness of 1 mm and a diameter of 200mm were prepared, and a through-hole with a diameter of 40 mm was formedin the center of each of the disks.

25 Insulating disks made of vinyl chloride with a thickness of 4 mm anda diameter of 199 mm were prepared, and a through-hole with a diameterof 40 mm was formed in the center of each of the disks.

The disks made of aluminum and the insulating disks were alternatelyarranged and fixed firmly with bolts. A power feeding layer made oftitanium with a diameter of 39 mm and a length of 250 mm was insertedinto the through-hole portion in the center, and fixed firmly with ajig. Thus, a drum electrode 1 was obtained, in which linear projectingelectrodes continuously extending in the circumferential direction witha width of 1 mm were formed at an interval of 4 mm.

The projecting electrodes of the drum electrode 1 thus obtained weresubjected to aluminum plating treatment in order to roughen the surfacesthereof.

<Production of Metal Porous Body 1>

(Base Material)

As a base material, foamed urethane with a thickness of 1 mm, a porosityof 95% by volume, and a number of pores (cells) per inch of about 50 wasprepared. By immersing the foamed urethane in a carbon suspension,followed by drying, electrical conductivity was imparted thereto. Thecarbon suspension contained 17% by mass of graphite and carbon black and7% by mass of a resin binder, and further contained a penetrating agentand an anti-foaming agent. The particle size of the carbon black was 0.5μm.

(Structure of Device for Producing Metal Porous Body)

As a plating solution, a molten salt was prepared by mixing aluminumchloride (AlCl₃) and 1-ethyl-3-methylimidazolium chloride (EMIC) at amixing ratio of 2:1 (in terms of molar ratio), and a plating tank wasfilled with the plating solution.

In the plating tank, an aluminum electrode was placed as an anode, andthe drum electrode 1 produced as described above was placed as acathode.

(Production of Metal Porous Body)

The foamed urethane to which electrical conductivity had been impartedas prepared above was supplied as a base material to the device forproducing a metal porous body having the structure described above, andaluminum electroplating was performed. Thereby, a metal porous body 1was produced. The conveying velocity of the base material was set at 17mm/min, and the applied current density was set at 8 A/dm².

Furthermore, a cutting bit was provided on the upper side of the drumelectrode 1 so as to be configured to appropriately cut aluminumelectrodeposited on the surfaces of the projecting electrodes. Thecutting bit was placed at a distance of 1 mm from the surface of theinsulating layer and was moved in a reciprocating manner in a directionorthogonal to the circumferential direction.

Example 2

<Production of Drum Electrode 2>

A drum made of aluminum with a diameter of 200 mm was prepared, and 24linear projections extending continuously in the circumferentialdirection were formed at an interval of 4 mm. The width of theprojections was set at 1 mm, and the height of the projections was setat 1.5 mm.

The entire surface of the aluminum drum was coated with a fluororesin(ETFE) with a thickness of 0.6 mm. Since the fluororesin layer was alsoformed on the surfaces of the projections, the surface coated with thefluororesin was scraped until the surfaces of the projections wereexposed. Aluminum plating was grown with a thickness of 0.5 mm on thesurfaces of the projections (aluminum) exposed from the surface of thefluororesin. Thus, a drum electrode 2 was obtained, in which linearprojecting electrodes 63 continuously extending in the circumferentialdirection with a width of 1 mm were formed at an interval of 4 mm. FIG.6 is an enlarged cross-sectional view of a surface portion of the drumelectrode 2. In FIG. 6, reference sign 62 denotes the insulating layermade of the fluororesin.

<Production of Metal Porous Body 2>

A metal porous body 2 was produced as in Example 1 except that the drumelectrode 2 was used instead of the drum electrode 1 in the productionof the metal porous body 1 in Example 1.

Example 3

<Production of Drum Electrode 3>

A drum made of aluminum with a diameter of 200 mm was prepared, and bysubjecting the surface thereof to anodic oxide coating treatment, ananodic oxide film of aluminum was formed. The thickness of the anodicoxide film of aluminum was about 10 μm.

On the surface of the drum on which the anodic oxide film had beenformed, 24 grooves continuously extending in the circumferentialdirection were formed at an interval of 4 mm. The width of the grooveswas set at 1 mm, and the depth of the grooves was set at 0.5 mm. Bysubjecting the surface of the drum to aluminum plating treatment,aluminum plating was grown in the grooves. Aluminum plating was formedso as to project from the surface of the anodic oxide film by 0.5 mm.Thus, a drum electrode 3 was obtained, in which linear projectingelectrodes 73 continuously extending in the circumferential directionwith a width of 1 mm were formed at an interval of 4 mm. FIG. 7 is anenlarged cross-sectional view of a surface portion of the drum electrode3. In FIG. 7, reference sign 72 denotes anodic oxide coating serving asan insulating layer.

<Production of Metal Porous Body 3>

A metal porous body 3 was produced as in Example 1 except that the drumelectrode 3 was used instead of the drum electrode 1 in the productionof the metal porous body 1 in Example 1.

Example 4

<Production of Drum Electrode 4>

A drum electrode 4 was produced as in Example 1 except that the width ofthe projecting electrodes was set at 2 mm and the width of theinsulating layer portion was set at 4 mm in the production of the drumelectrode 1 in Example 1.

<Production of Metal Porous Body 4>

A metal porous body 4 was produced as in Example 1 except that the drumelectrode 4 was used instead of the drum electrode 1 in the productionof the metal porous body 1 in Example 1.

Example 5

<Production of Drum Electrode 5>

A drum electrode 5 was produced as in Example 1 except that the width ofthe projecting electrodes was set at 2 mm and the width of theinsulating layer portion was set at 8 mm in the production of the drumelectrode 1 in Example 1.

<Production of Metal Porous Body 5>

A metal porous body 5 was produced as in Example 1 except that the drumelectrode 5 was used instead of the drum electrode 1 in the productionof the metal porous body 1 in Example 1.

Example 6

<Production of Drum Electrode 6>

24 Disks made of copper with a thickness of 1 mm and a diameter of 200mm were prepared, and a through-hole with a diameter of 40 mm was formedin the center of each of the disks.

25 Insulating disks made of vinyl chloride with a thickness of 4 mm anda diameter of 199 mm were prepared, and a through-hole with a diameterof 40 mm was formed in the center of each of the disks.

The disks made of copper and the insulating disks prepared as describedabove were alternately arranged and fixed firmly with bolts. A powerfeeding layer made of titanium with a diameter of 39 mm and a length of250 mm was inserted into the through-hole portion in the center, andfixed firmly with a jig. Thus, a drum electrode 6 was obtained, in whichlinear projecting electrodes continuously extending in thecircumferential direction with a width of 1 mm were formed at aninterval of 4 mm.

<Production of Metal Porous Body 6>

A metal porous body 6 was produced as in Example 1 except that a copperplating solution was used as a plating solution instead of the aluminumplating solution, a copper electrode was used as the anode instead ofthe aluminum electrode, and the drum electrode 6 was used instead of thedrum electrode 1 in the production of the metal porous body 1 inExample 1. The copper plating solution used was composed of 70 g/L ofcopper sulfate and 200 g/L of sulfuric acid.

Example 7

<Production of Drum Electrode 7>

A drum electrode 7 was produced as in Example 6 except that insulatingdisks with a width of 9 mm were used in the production of the drumelectrode 6 in Example 6.

<Production of Metal Porous Body 7>

A metal porous body 7 was produced as in Example 6 except that the drumelectrode 7 was used instead of the drum electrode 6 in the productionof the metal porous body 6 in Example 6.

[Evaluation of Metal Porous Bodies]

In the metal porous bodies produced in Examples 1 to 7, it was confirmedthat aluminum or copper was satisfactorily plated on the surface of thefoamed urethane. The variation in the coating weight of aluminum orcopper in the width direction was within ±15% of the targeted coatingweight.

REFERENCE SIGNS LIST

1 drum electrode

11 power feeding layer

12, 42, 62, 72 insulating layer

13, 43, 63, 73 projecting electrode

22, 52 insulating disk (insulating layer)

23, 53 metal disk (projecting electrode)

32 divided insulating disk (insulating layer)

81 existing drum electrode

82 projection

83 anode

84 plating tank

85 plating solution

1. A drum electrode for a device configured to plate a surface of a longbase material having electrical conductivity with a metal, the drumelectrode comprising: a power feeding layer; an insulating layer whichcovers a surface of the power feeding layer; and a projecting electrodewhich projects from the surface of the insulating layer and iselectrically connected to the power feeding layer, wherein theprojecting electrode is provided linearly in the circumferentialdirection of the drum electrode.
 2. The drum electrode according toclaim 1, wherein the height of the projecting electrode varies with thelocation of the projecting electrode on the drum electrode.
 3. The drumelectrode according to claim 1, wherein the base material is a resinmolded body having a three-dimensional network structure.
 4. A methodfor producing a drum electrode comprising: a step of covering a surfaceof a columnar power feeding layer with an insulating layer; a step ofpartially removing the surface of the insulating layer linearly in thecircumferential direction so as to expose the surface of the powerfeeding layer; and a step of plating the linearly exposed surface of thepower feeding layer with a metal to form a projecting electrode so as tobe higher than the surface of the insulating layer.
 5. A method forproducing a drum electrode comprising: a step of alternately stackingring-shaped insulating disks and ring-shaped metal disks, each having athrough-hole in the center thereof, to form a cylindrical shape; and astep of inserting a columnar power feeding member into the through-holesof the insulating disks and the metal disks, followed by fixing.
 6. Aplating device configured to plate a surface of a long base material, towhich electrical conductivity has been imparted, with a metal using adrum electrode provided in a plating tank, wherein the drum electrode isthe drum electrode according to claim
 1. 7. A method for producing aresin structure comprising: a step of imparting electrical conductivityto a surface of a long base material made of a resin; and a step ofplating the surface of the base material with a metal using a drumelectrode provided in a plating tank to obtain a resin structure havinga metal plating film on the surface thereof, wherein the drum electrodeis the drum electrode according to claim
 1. 8. A method for producing ametal porous body comprising: a step of imparting electricalconductivity to a surface of a resin molded body having athree-dimensional network structure; a step of plating the surface ofthe resin molded body with a metal using a drum electrode provided in aplating tank to obtain a resin structure; and a step of removing theresin molded body from the resin structure to obtain a metal porousbody, wherein the drum electrode is the drum electrode according toclaim 1.